Kenya's national track federation is investigating claims of increased doping among its famed distance athletes and has asked the World Anti-Doping Agency and police for help.

Athletics Kenya chairman Isaiah Kiplagat told The Associated Press on Thursday that the federation was looking into allegations by a German reporter and an athlete that performance-enhancing substances were being made available to runners by people posing as doctors.

WADA said it is aware of the allegations, has communicated with "the relevant authorities" and would "monitor the inquiry."

Kiplagat insisted Kenyan runners were "very clean" but his federation wanted to know the cause of the allegations.

Four Kenyans have been sanctioned this year by the IAAF for doping offenses. Others have reportedly failed tests, including one who said many of his compatriots were doping.